Calcium is commonly present in water sources, a natural occurrence as water picks up minerals from the environment. Its presence has varied implications for consumers, from household effects to health considerations.
How Calcium Enters Water
Calcium enters water primarily through natural geological processes. As rainwater seeps into the ground or flows over land, it interacts with rock formations. Water becomes weakly acidic by absorbing carbon dioxide from the atmosphere, forming carbonic acid, which dissolves minerals from rocks.
Significant sources of calcium include rocks rich in calcium-containing minerals, such as limestone, chalk, and gypsum. As water passes through or over these abundant rocks, it dissolves calcium carbonate and other calcium salts, carrying them into groundwater and surface water supplies.
Understanding Hard Water
Water with a high concentration of dissolved minerals, predominantly calcium and magnesium, is known as hard water. The level of hardness can vary, with soft water generally containing 0 to 60 milligrams per liter (mg/L) of calcium carbonate, moderately hard water 61 to 120 mg/L, hard water 121 to 180 mg/L, and very hard water exceeding 180 mg/L. This mineral content leads to several noticeable household effects.
Hard water reduces the effectiveness of soaps and detergents. It reacts with soap to form a sticky residue known as soap scum, making it harder to lather and clean effectively. This residue can cling to skin and hair, potentially leading to dryness and irritation, and can also leave clothes feeling stiff or looking dull after washing.
Mineral buildup, or limescale, is another significant problem caused by hard water. When heated, dissolved minerals, particularly calcium carbonate, precipitate and form hard deposits. These deposits accumulate in pipes, water heaters, dishwashers, and coffee makers, reducing appliance efficiency and shortening their lifespan. Limescale can also cause unsightly stains on fixtures and leave spots or a cloudy film on dishes and glassware.
Calcium in Water and Your Health
Calcium is an essential mineral for human health, playing a role in bone strength, muscle function, and nerve signaling. While dietary sources like dairy products and leafy greens are primary contributors, drinking water can provide a supplemental source of calcium. For some individuals, particularly those with dietary restrictions or insufficient intake from food, waterborne calcium can be a beneficial addition.
Concerns about calcium in water and kidney stones are common, but the relationship is nuanced. While calcium oxalate stones are the most prevalent type of kidney stone, the calcium in drinking water is generally not considered a primary cause for most people. Some research suggests that adequate dietary calcium, including from water, can even be protective against kidney stone formation in certain individuals. Individual factors and high overall intake may influence risk, especially in specific subgroups like older adults or females.
Research on the connection between calcium in drinking water and cardiovascular health has yielded mixed results. Some studies indicate that higher levels of calcium and magnesium in water may be associated with a reduced risk of cardiovascular diseases, including acute myocardial infarction and ischemic heart disease. This potential benefit is often attributed to the overall mineral content of hard water. Further research is needed to fully understand the specific mechanisms and confirm these associations, as confounding factors can influence findings.
Testing and Treating Water for Calcium
Consumers can determine calcium levels in their water through various methods. Home testing kits offer a convenient way to get an initial indication of water hardness. For more precise measurements, professional water testing services can analyze a water sample and provide detailed reports. Municipal water quality reports, often available online, also provide information on local water hardness.
Several methods reduce or remove calcium from water. Water softeners, which typically use an ion exchange process, are a common residential solution. These systems contain resin beads that attract calcium and magnesium ions, replacing them with sodium or potassium ions, thereby softening the water. This process effectively prevents limescale buildup and improves soap performance.
Reverse osmosis (RO) systems offer a more comprehensive filtration method. RO works by forcing water through a semi-permeable membrane with tiny pores, which effectively blocks many contaminants, including 93% to 99% of calcium. While RO produces highly purified water, it also removes other beneficial minerals, sometimes leading to a “flat” taste. Distillation is another method that involves heating water to create steam, leaving minerals like calcium behind, and then condensing the steam back into purified water. This process can remove nearly all impurities, including calcium.